POV-Ray : Newsgroups : povray.advanced-users : Telephoto lens effect Server Time
30 Jul 2024 00:30:30 EDT (-0400)
  Telephoto lens effect (Message 1 to 6 of 6)  
From: Francois Labreque
Subject: Telephoto lens effect
Date: 24 Nov 2000 10:14:00
Message: <3A1E8557.91062A0@videotron.ca>
Does (mega)POV do like real telephoto lenses do and "shrink" the
distance of far away objects?

Should I just RTFM more?
-- 
Francois Labreque | It is by caffeine alone I set my mind in motion, it
    flabreque     | is by the beans of Java that thoughts acquire speed,
        @         | the hands acquire shaking, the shaking becomes a 
   videotron.ca   | warning, it is by caffeine alone I set my mind in
                  | motion.
                               - Stolen from Badger's .sig file


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From: Chris Huff
Subject: Re: Telephoto lens effect
Date: 24 Nov 2000 17:33:56
Message: <chrishuff-0A18F8.17342424112000@news.povray.org>
In article <3A1### [at] videotronca>, Francois Labreque 
<fla### [at] videotronca> wrote:

> Does (mega)POV do like real telephoto lenses do and "shrink" the
> distance of far away objects?

Look up the "angle" keyword for the camera.


> Should I just RTFM more?

Yep. Specifically, this part of the fine manual:
4.4.1.3 Angle
    The angle keyword followed by a float expression specifies the 
(horizontal) viewing angle in degrees of the camera used.
...snip...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><


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From: Margus Ramst
Subject: Re: Telephoto lens effect
Date: 24 Nov 2000 19:01:42
Message: <3A1F01BA.261970AF@peak.edu.ee>
Chris Huff wrote:
> 
> Look up the "angle" keyword for the camera.
> 

One thing about "angle": with panoramic projection it must be the first keyword
in the camera block, in order to take effect.

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg


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From: Francois Labreque
Subject: Re: Telephoto lens effect
Date: 24 Nov 2000 21:15:57
Message: <3A1F2079.6D3E4395@videotron.ca>
Chris Huff wrote:
> 
> In article <3A1### [at] videotronca>, Francois Labreque
> <fla### [at] videotronca> wrote:
> 
> > Does (mega)POV do like real telephoto lenses do and "shrink" the
> > distance of far away objects?
> 
> Look up the "angle" keyword for the camera.
> 

I did.  And it does not appear to be giving the desired effect.

I am talking about the fact that when you are taking pictures with a
zoom, the apparent depth of the scene shrinks.  i.e. objects directly in
front of you will appear relatively closer to each other than they
really are, such as here:

http://www.americascup.org/gallery/ac/race_04/030100_TNZvsPRA_s/assets/acp20000301mcl4zr70883ph7.jpg

(watch the word wrap)

Where it looks as if the two boats were about to hit each other when in
fact they were probably a few hundred feet apart.

-- 
Francois Labreque | It is by caffeine alone I set my mind in motion, it
    flabreque     | is by the beans of Java that thoughts acquire speed,
        @         | the hands acquire shaking, the shaking becomes a 
   videotron.ca   | warning, it is by caffeine alone I set my mind in
                  | motion.
                               - Stolen from Badger's .sig file


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From: Margus Ramst
Subject: Re: Telephoto lens effect
Date: 25 Nov 2000 01:28:52
Message: <3A1F5C79.2FEEA4DF@peak.edu.ee>
Francois Labreque wrote:
> 
> I did.  And it does not appear to be giving the desired effect.
> 
> I am talking about the fact that when you are taking pictures with a
> zoom, the apparent depth of the scene shrinks.

"Angle" does do just that. Basically, reducing the camera angle reduces the
perspective effect; angle -> infinity approaches orthographic projection.
Remember that reducing the camera angle reduces the FOV (Field of View). So if
you want a particular object to appear the same size as before, you need to
increase the distance between it and the camera.

-- 
Margus Ramst

Personal e-mail: mar### [at] peakeduee
TAG (Team Assistance Group) e-mail: mar### [at] tagpovrayorg


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From: Francois Labreque
Subject: Re: Telephoto lens effect
Date: 25 Nov 2000 09:24:50
Message: <3A1FCB4C.431D3AD5@videotron.ca>
Margus Ramst wrote:
> 
> Francois Labreque wrote:
> >
> > I did.  And it does not appear to be giving the desired effect.
> >
> > I am talking about the fact that when you are taking pictures with a
> > zoom, the apparent depth of the scene shrinks.
> 
> "Angle" does do just that. Basically, reducing the camera angle reduces the
> perspective effect; angle -> infinity approaches orthographic projection.
> Remember that reducing the camera angle reduces the FOV (Field of View). So if
> you want a particular object to appear the same size as before, you need to
> increase the distance between it and the camera.

After I wrote my last reply, last night, I played around and got
satisfying results.

Thanks anyway.

-- 
Francois Labreque | It is by caffeine alone I set my mind in motion, it
    flabreque     | is by the beans of Java that thoughts acquire speed,
        @         | the hands acquire shaking, the shaking becomes a 
   videotron.ca   | warning, it is by caffeine alone I set my mind in
                  | motion.
                               - Stolen from Badger's .sig file


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